Electrothermal cut-out.



No. 845,219. I PATENTED FEB. 26, 1907.

P. B, 000K.

ELEOTROTHERMAL GUT-OUT.

APPLICATION FILED APR.16, 1906.

WITNESSES; INVENTURl UNITED STATES PATENT OFFICE.

Specification of Letters Patent.

Patented Feb. 26, 1907.

Application filed April 16. 1906- Serial No. 811,992.

To all whom it may concern.-

Be it known that I, FRANK B. 000K, 2. citizen of the United States of America, residing at Chicago, in the county of (look and State 'of Illinois, have invented a new and useful Electrotliermal Out-Out, of which the following is a specification, reference being had to the accompanying drawings, illustrating same.

Myinvention relates to electrothermal protectors for protecting electrical circuits and apparatus from abnormally-large currents of electricity, and especially to such protectors adapted to protect the circuits and apparatus from small increments of electrical currents generally termed sneak-currents.

The principal objects of my invention are to provide an electrothermal protector of this class which is held in operative position by non-conducting cementing material and to arrange the actuating means to close the electrical circuit through the protector without depending upon the cementing material.

This present invention is an improvement on my copending application for Letters Patent on electrical protective apparatus filed March 8, 1906, Serial No. 304,929.

It is generally customary to provide an electrothermal protector with a metallic solder for seeming certain portions thereof against operation, the solder being softened by heat produced in the device by an abnormally-large current of electricity to allow the apparatus to operate, and also forming part or the conductive circuit. In this present in ventionI arrange the parts so that the electrical circuit through the device is completed without depending upon the cementing material and hold the parts in operative position by non-conducting cement or wax, which is softenable by heat produced in the device, to allow the apparatus to operate.

Referring to the accom' anying drawings,

illustrating the preferred rorm of my invention, Figure 1 is a side view of the protector of the invention in connection with its supporting and operating members. Fig. 2 is a plan view of Fig- 1 with an end portion of the protector removed.

Like characters refer to like parts in the several figures.

The heating element preferably used comprises a piece of carbon or graphite 1, to which are properly secured conducting end .ca s 2 and 3. In securin the end ca s 2 and 3 to the heating element 1 the latter is pref erably metallically plated on the ends and the caps soldered thereto by hard solder. End cap 3 is provided with a stem 4, whichis threaded and screwed into a threaded portion 5 of a supporting member 6. '1 his threaded connection firmly holds the protector in place at all times. The end cap 2 is provided with a neck portion 7 and a head 8 thereon, forming an annular recess adapted to receive the free end 9 of spring member 10. The free end 9 of spring member 10 is split, as at 11, and formed so as to grip the neck portion 7 when spring 10 is engaged with the protector, as shown in Fig. 1. The splitll enables the free end 9 of spring 10.to spring apart somewhat when engaged with the protector, and thereby iirmly gripthe neck portion 7 and make a good electrical connection therewith. The free end 9 of spring 10 also preferably bears against.the end of cap 2, which also helps to make an electrical connection between the spring 10 and the protector. e

The free end 9 of spring 10 does not grip the neck portion 7 sufliciently to hold spring 10 in a set position against its tension without assistance. To assist in holding spring 10 in this set position, as shown in Fig. 1, I

provide an insulating cenienting ntaterial 12, r

such a sof tenable wax, between the head 8 and portion 9 to adhere to these porlions and hold spring 10 in a set position when the wax 12 is cool. \Vhen the wax 12 is heated, however, it becomes soft, and thereby allows spring 10 to separate from the protector and take the position 13; (Shown in dotted lines in Fig. 1.) lVhen this protector is used in connection with telephone -swil -hho:ird apparatus, the spring 10 is preferably conneeted through a conductor 14 to the swiirhboard, and sup-port 6 is preferably connected through'a conductor 15 to the line. It will be seen that when the device operates the circuit is opened between the suiwhboard and line at the protector, which entirely dis connects the suitchboard from the objectionable current coming from the line.

The operation oi'the device is as follows: When an abnormally large current of electricity traverses the heating element 1 for a sufficient length of time, depending upon the strength of the current, it produces heat in 1,

allows the latter to separate from the neck which heat is conducted to the softenable cementing material 12 to soften same. When the cementing material 12 is sufliciently softened, it releases its hold upon spring 10 and portion 7 and take the position 13, which opens the circuit through the protector. When the protector cools, the wax 12 becomes hard and nearly fills up the recess at the end of the protector, especially on the side from which spring 10 was pulled. As this recess is now partially obstructed, spring 10 cannot be set entirely back to operative position unless the wax is heated or unless it is forced through the wax.

It will readily be seen that this protector may be operated again when properly reset. In resetting the protector it is only necessary to reh at the wax 12, push the spring 10 back to reset position and hold same there until the wax cools. A'convenient way of accomplish'ing the resetting of this device is to ap ply a resetting-tool thereto in a 1r anner similar to that described in my copending application above mentioned.

It is not believed to be necessary to here describe the resetting of the protector in detail, as this is fully done in the said copending application. It is believed to be sufli cient here to merely show that the protector can be reset and reoperated, in fact, as many times as desired.

I do not wish to limit this invention to the particular details of construction as herein shown or to any any particular insulating wax or cementing material. As a cementing material beeswax, Japanese wax, shellac, palm-tree wax, stearin, parafiin, or resin may be used with very satisfactory results.

W'hat I claim as my invention, and desire to secure, by Letters Patent, is

1. A thermal protector comprising a piece of homogeneous resistance material, suitable end caps therefor and secured thereto, a suitable support connected to one of the end caps by a screw connection, an operable spring member electrically connected with the other end cap by hearing against same, i and insulating-wax securing the said spring member to itsend cap.

2. An electrical protector comprising a heating element, a terminal cap therefor,a spring member engaging the terminal cap, a split in the spring 1:: ember to allow the latter to firmly grip a portion of the terminal cap, 1

and insulating cementing material normally holding the spring member in connection with the terminal cap.

3. A thermal protector comprising a heating element, a terminal therefor, a spring member provided with a slotted split portion adapted to bear against and grip a portion of the terminal, and heat-susceptible insulating cementing material normally holding the spring member in connection with the terminalv 4. A thermal protector comprising a heatproducing element, n'ieans for securely supporting same, a teririnal cap for the heating element provided with a small neck portion and a head to form an annular recess, a spring member provided with a slot adapted tofit over the neck portion, and a split extending from the bottom of the slot to allow the spring member to firmly grip the neck portion in the slot to make good electrical connection therewith, and heat-susceptible insulating material in the said recess normally holding the spring member in place in connection with the said neck portion, when cool.

5. A thermal protector comprising a piece of graphite and a metallic terminal on each end thereof, a spring-support for the protector, a threaded portion on one said; terminal making screw connection with the said sup port, anannular recess on the other said terminal, a spring member the free end of which bears against the last-mentioned terminal so as to make electrical connection therewith, and heat-susceptible insulating material in the annular recess normally holding the spring member in connection with its terminal. I

6. An electrothermal protector comprising heat-producing means and means for securely mounting same, a terminal for the heat-producing means provided with an annular recess, a springmember engaging the terminal in the annular recess, and heat-susceptible insulating material i1v the annular recess normally holding the spring member therein. I

As inv tor'of the foregoing .I hereunto subscribe-my name, in the presence of two subscribing witnesses, this'12th. day of Apr-il, 1906.

FRANK B. COOK;- /Vitnesses:

E. N. STEPHENSON, JNo. F. TOMPKINS. 

